GB2074682A

GB2074682A - Saddle for branch connection to a main pipe

Info

Publication number: GB2074682A
Application number: GB8013791A
Authority: GB
Original assignee: Hitachi Metals Ltd
Current assignee: Proterial Ltd
Priority date: 1980-04-25
Filing date: 1980-04-25
Publication date: 1981-11-04

Abstract

A saddle for service connection a street main 1 comprises a sleeve body top half 3 and a sleeve body bottom half 7, both of which are positioned to surround the street main and are bolted to each other. The sleeve body top half 3 comprises a saddle body having an inside curved surface for receiving the street main 1, a boss 35 on the saddle surface for receiving a service pipe and a through-opening 33 on the saddle under the boss for connecting the service pipe from the main pipe through the boss, wherein the through-opening 33 is a oval-like form, which long diameter is approximately equal to the boss inside diameter. <IMAGE>

Description

SPECIFICATION Hot tap saddle for service connection on street pipe and method of service connection Background of the invention The present invention relates to a hot tap saddle for a service connection for use in newly branching a service pipe for residences from a buried street main pipe for gas, etc., and particularly to a structure of a pipe fitting for use in connecting the service pipe with an aperture equal or approximate to that of the street pipe and also a process of boring a hole in the street main.

Description of the prior art: When a service is branched from a laid main, the pipe fitting of saddle type is employed generally. Such a pipe fitting is composed of a top boss having a means for connecting the service pipe or other pipefittings, a saddle body with a curved surface for receiving the outside surface of the street main and a fastening member such as U-bolt or fastening the body to the main. The boss on the saddle body has an orifice communicating with the internal arcuate surface so that the service pipe connected on the boss communicates with the main through an opening bored on the street main at the boss. The arcuate surface of the saddle body has an annular groove surrounding the orifice, in which an annular gasket is secured to prevent gas leakage from between the outside surface of the street main and the arcuate surface of the saddle body.

When the aperture of the service pipe is comparatively small relative to that of the street main, the annular gasket is secured between the outside surface of the street main and the inside walls of the annular groove to completely prevent a gas leakage. However, when the aperture of the service pipe equals or approximates to the diameter of the street main, it is difficult to prevent the gas leakage with a gasket. That is, as shown in Fig. 1, the gasket inserted in the annular groove 22 formed in the arcuate surface 21 of the saddle body 2 is shaped open downward at both sides of the street main 1 so that the gasket comes in imperfect contact with the street main 1.

When the aperture of the orifice 23 at lower portion of the saddle body 2 is comparatively large, it is difficult that the annular groove 22 formed radially to a street main from the arcuate surface is positioned on both sides of the main 1 by the general manufacturing process, such as casting. On the other hand, if the orifice in the saddle body 2 and the hole 10 bored in the main 1 are comparatively small to complete leakage-proof, the gas flow rate from the main 1 to the service pipe will not be assured.

As described, with the hot tap saddle it is difficult to branch from the street main the service pipe with the same aperture as the street main. In such a case, the street main is partially cut away and the resulted space is inserted with a pipe fitting of T type. In this step, it is required to block both ends of cut space of the main with rubber bags and to form a costly bypass circuit for gas supply during construction of branch pipe connection.

Summary of the invention: The object of the present invention is to provide a pipe fitting of hot tap saddle type capable of connecting a service pipe with the aperture equal or approximate to that of a street main.

Another object of the present invention is to provide a process for boring the street main in order to connect the laid main with the service pipe of an aperture equal or approximate to that of said main.

The saddle body of the hot tap saddle according to the present invention comprises an inside arcuate surface for receiving a street main, a boss on the saddle surface for receiving a service pipe or a pipe fitting and a through-opening of oval like form on the saddle under the boss for connecting the service pipe from the main pipe through the boss.

The opening may be a long hole along the axis direction of the main. The width of the long hole is narrow enough to provide a sufficient area for gasket. The saddle body is to be fixed on a street main. The length of the hole is preferable to be equal to the inside diameter of the boss.

For communicating the main pipe to communicate with the saddle body of the hot tap saddle comprises a plurality of holes having each diameter substantially equal to the width of the oval-form opening in said saddle body are bored on the main pipe. The number of the bored holes is at least two which are shifted in the axial direction of said main pipe.

These holes may be formed one over another within the area of the oval-form opening so as to present an opening area approximate to the area of the oval-form cpening.

Brief description of the drawings: Figure 1 is a sectional view of a hot tap saddle positioned on a street main, showing a disadvantage of the conventional saddle; Figure 2 is a plain view of a hot tap saddle of this invention positioned on a street main; Figure 3 is a sectional view of the hot tap saddle on the line 3-3 in Fig. 2; Figure 4 is a sectional view on the line 4-4 in Fig. 2; and Figure 5 shows a drilling operation of the main pipe.

Description of the preferred embodiments: The hot top saddle for a service connection on a street main, according to the present invention, is being explained referring to Figs.

2 to 4. It is apparent from Fig. 3 that the present pipe fitting comprises a top half 3 and a bottom half 7 of a sleeve body, wherein the arcuate surfaces 31 and 71 of the both halves are fastened with the bolt-nuts 5, 6 inserted through the flanges 39, 79 protruded rectangularly to the axis of a main 1 to be connected with a service pipe. The bolts 5 and the bottom half 7 may be incorporated together to form a U-bolt. A female screw 34 for connecting with a service pipe or other pipe fitting is incorporated with the top boss 35 on the top half of the saddle body. Alternatively other mechanical connection, such as flanges, may be used to connect the top boss with the service pipe.

An oval-form opening 33 reaching the saddle surface 31 is formed on the saddle body to follow a true-circular opening 36 for a female screw 34 in utmost interior of a boss opening 35 of the saddle body top half 3.

The oval-form opening 33 is, as shown in Fig. 2, extending in the axial direction of the main pipe 1 which length is approximately equal to the diameter of the opening 36. A groove 32 is formed to mount a gasket 4 surrounding the oval-form opening 33. The minor diameter of an oval-form opening 33, or the width rectangular to the axis of the main 1, is small enough so that the groove 32, as shown in Fig. 3, can be formed to have not only the inner peripheral wall 37 but also the outer peripheral wall 38 of the groove above the outer surface of the main.

The gasket 4 in the groove 32 of this structure assures a gas-proof between the arcuate surface 31 and the outer surface of the main.

The opening bored in the main pipe 1 may contain two holes of a diameter slightly smaller than the minor diameter of the ovalform opening 33 of the saddle body 3 so that the opening 11 bored in the main 1 communicates with the main 1.

The centers of holes 11 a and 11 b are shifted a little in the axial direction so that holes 11 a and 11 b are positioned within the stretch of major diameter of the oval-form opening of the saddle body 3. Accordingly the opening 11 formed of the overlaid holes 11 a and 11 b to open in the main pipe has such a shape and opening area as to cover the ovalform opening 33 of the saddle body 3.

Fig. 5 presents an example of the process for boring two holes in the street main 1. A jig 8 for carrying a hole saw 9 is mounted in the upper opening 35 of the saddle body 3 of the hot tap saddle fastened to the main 1.

The axis of a boss 81 for supporting the axis 91 of the hole saw 9 in the jig 8 is disposed in a position a little shifted in the axial direction of the main pipe relative to the axis of the opening 35 of the saddle body 3. In order to bore the main pipe, at first the jig 8 is so mounted that the axis of the hole saw 9 is positioned on one side 90a of the axis of the main pipe relative to the axis 30 of the saddle body 3, thus boring a hole 11 a, then the jig 8 is so mounted that the axis of the hole saw 9 may be positioned on the other side 90b, thus boring the other hole (not presented in the drawing).

As the inner diameter of the upper opening 35 of the saddle body 3 becomes larger, the major diameter of oval-form opening in the lower part may be increased so that the area of the oval-form opening is enlarged. In the case where the major diameter is excessively large relative to the minor diameter of the oval-form opening, three holes should be bored in the main pipe, and the composite form from the holes overlaid together should approximate the form of said oval-form opening.

The oval-form opening of the hot tap saddle is not necessarily a geometrically correct ovalform, but also may be longer in the axial direction of the main pipe and be small in the width perpendicular to the axis, thus the area of the opening may be just sufficient to supply gas to the service pipe. Also the holes bored in the main pipe as a whole correspond to said oval-form opening, though the aperture of individual hole and the number of holes may not be particularly defined.

Furthermore it should be construed that the pipe fitting of hot tap saddle type according to the present invention may be modified without deviating from the technical idea of the present invention in the shape etc. or other parts.

Claims

1. A hot tap saddle for service connection on street pipe comprising a sleeve body top half and a sleeve body bottom half, the sleeve body top half including a first saddle body and a flange along each side of the saddle body with holes for receiving bolts, the first saddle body having an inside surface for receiving a main pipe, a boss on the saddle surface for receiving a service pipe, a through-opening on the saddle under the boss for connecting the service pipe from the main pipe through the boss, the through-opening being an oval-like form, and a gasket surrounding the through-opening for gas-proof between the inside curved surface and the main pipe, the sleeve body bottom half including a second saddle body having an inside surface for receiving the main pipe and a flange along each side of the second saddle body with holes for receiving bolts.

2. The hot tap saddle as set forth in claim 1, wherein the length of the through-opening is substantially equal to the inside diameter of the street main pipe.

3. The hot tap saddle as set forth in claim 1, wherein the through-opening is a plurality of round holes continuously formed along the axis of the saddle.

4. The hot tap saddle as set forth in claim 3, wherein the through-opening is made of two round holes over-lapping by formed along the axis of the saddle.

5. A method of service connection on street main pipe comprising: setting a sleeve body top half on the street main pipe, the sleeve body top half including a first saddle body and a flange along each side of the first saddle body with holes for receiving bolts, the first saddle body having an inside surface for receiving a main pipe, a boss on the saddle surface for receiving a service pipe, a through-opening on the saddle under the boss for connecting the service pipe from the main pipe through the boss, the through-opening being an orbit-like form, and a gasket surrounding the through-opening for gas-proof between the inside curved surface and the main pipe, bolting the sleeve body top half and a sleeve body bottom half, the sleeve body bottom half including a second saddle body having an inside surface for receiving the main pipe and a flange along each side of the second saddle body with holes for receiving bolts, and drilling the street main pipe to form a plurality of holes along the axis of the main pipe within the area of the oval opening.

6. The method as set forth in claim 5, wherein the plurality of holes is formed of two overlapping holes.

7. The method as set forth in claim 5, wherein the hole if formed by a hole saw which axis is positioned eccentrically to the axis of the boss.